According to the movie Jurassic Park and every small child, dinosaurs were only capable of one noise: a fierce and deafening roar. But a team of scientists now say dinosaurs may have made a wider variety of sounds, including a cooing sound like that of the common pigeon.
Researchers from Midwestern University and University of Texas at Austin looked at over 200 species of modern birds and when their ancestors evolved the ability to make closed-mouth vocalizations. These sounds include hooting, booming, and cooing, and are produced when birds inflate an expandable throat cavity like a balloon. Birds that make these kinds of calls use them in mating and courtship rituals, as in this video of the sage grouse’s mating display:
The researchers, whose findings (paywall) were published July 13 in the journal Evolution, found that closed-mouth vocalizations commonly evolved in larger members of the archosaur group, which includes birds, crocodilians, and dinosaurs.
Whether the massive Tyrannosaurus rex cooed like a dove is still unclear, though. The researchers can’t say for sure what dinosaurs sounded like because “behavior doesn’t fossilize,” said Chad Eliason, one of the authors of the paper and a biologist at the University of Texas. But the number of times archosaurs have evolved to make coos or booms, and the large size of most dinosaurs, suggests “this behavior may have been at least possible” for dinosaurs.
Eliason said body size and an expandable throat cavity seem to be key to making calls. Before any of the lineages evolved to make these vocalizations, they all evolved to be larger than 100 grams (3.5 ounces), or about the size of a modern-day dove. “Blowing up a small balloon is harder than blowing up a large balloon,” whether you’re at a birthday party or you’re a bird, he explained.
In any case, kids and filmmakers can be assured of one thing: Whether the big lizards cooed or roared, they were still probably pretty terrifying.